1. Field of the Invention
The present invention relates to an image processing device, an image processing method, and an image forming apparatus including the image processing device.
2. Description of the Related Art
Electrophotographic or inkjet image forming apparatuses are known in forms of copying machines, optical printers, optical plotters, facsimile machines, multifunction peripherals, and the like.
Such an image forming apparatus performs image formation based on input image data, which is data representing an image to be formed.
Examples of the input image data include scan data obtained by reading an original document with a scanner, data generated by a computer or the like, and data supplied via a communication line.
Other examples of the input image data include image data obtained by photographing using a digital camera or an image capturing apparatus of various types and image data generated by image editing software.
These image forming apparatuses generally apply “image processing of various types” to the input image data so that output image data for use in forming a desired image can be obtained.
The output image data may be output as an image formed onto a recording medium, such as recording paper, or displayed as an output image on a display device of various types.
There are known various image processing methods, some of which employ spatial frequency enhancement (as disclosed in, for instance, Japanese Laid-open Patent Application No. 2004-171231 and Japanese Patent No. 4821611).
A visible output image formed from output image data is generally a two-dimensional image. It is preferable that visually-perceived depth and material's texture intrinsic to a subject of the image are reproduced favorably.
A technique disclosed in Japanese Laid-open Patent Application No. 2004-171231 relates to reproduction of an image of “a condition of crevices, dikes, and the like on a cut surface of rock or rock outcropping” and achieves favorable reproduction of depth perception in the image.
A technique disclosed in Japanese Patent No. 4821611 is directed at reproduction of an image that is a “visceral radiograph” and successfully achieves enhancement of a desired observational portion of the image.
However, the techniques disclosed in Japanese Laid-open Patent Application No. 2004-171231 and Japanese Patent No. 4821611 are limited in “photograph subjects to be displayed as output images”.
Possible subjects of input images have a wide range of variations. Image processing that increases reproducibility of perceived depth and material's texture in output images of subjects of a wide range of variations is not known yet.
There is a need for an image processing device capable of generating, from input image data of a subject of a wide variety of types, output image data that is increased in visually-perceived surface roughness and texture intrinsic to the subject.
There is a need for an image processing method that allows generating, from input image data which is image data of a subject of a wide range of types, output image data that is increased in visually-perceived surface roughness and texture intrinsic to the subject.
There is also a need for an image forming apparatus including the image processing device.
The present invention at least partially solves the problems in the conventional techniques.